Both solutions are up and running, the problem I have is that they both stop working after a while and need to be fully turned off and back on again in order to work.
That is not very precise. Do the boards start smoking and spitting plastic when they "stop working"? It is how they fail, not that they fail, that is important.
Maybe if you posted your code... 
BTW, mine used to do that. It would go many hours, then lock up. It ended up being the SD reader SPI interface that was interfering with the w5100 SPI.